Open AccessSize-specific apparent survival rate estimates of white sharks using mark–recapture models
Author(s) -
Paul Kanive,
Jay J. Rotella,
Salvador J. Jorgensen,
Taylor K. Chapple,
James E. Hines,
Scot D. Anderson,
Barbara A. Block
Publication year - 2019
Publication title -
canadian journal of fisheries and aquatic sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 153
eISSN - 1205-7533
pISSN - 0706-652X
DOI - 10.1139/cjfas-2018-0142
Subject(s) - carcharias , biology , foraging , mark and recapture , vital rates , fecundity , ecology , abundance (ecology) , population , predation , white (mutation) , optimal foraging theory , fishery , zoology , demography , population growth , juvenile , biochemistry , gene , sociology
For species that exist at low abundance or are otherwise difficult to study, it is challenging to estimate vital rates such as survival and fecundity and common to assume that survival rates are constant across ages and sexes. Population assessments based on overly simplistic vital rates can lead to erroneous conclusions. We estimated sex- and length-based annual apparent survival rates for white sharks (Carcharodon carcharias). We found evidence that annual apparent survival differed over ontogeny in a system with competitive foraging aggregations, from 0.63 (standard error (SE) = 0.08) for newly recruiting subadults to 0.95 (SE = 0.02) for the largest sharks. Our results reveal a potential challenge to ontogenetic recruitment in a long-lived, highly mobile top marine predator, as survival rates for subadult white sharks may be lower than previously assumed. Alternatively, younger and competitively inferior individuals may be forced to permanently emigrate from primary foraging sites. This study provides new methodology for estimating apparent survival as a function of diverse covariates by capture–recapture study, including when sex assignment is uncertain.